1. Field of the Invention
This invention relates to a method for continuous production of polycarbonate-polyether-blockcopolymers.
2. Brief Description of the Background of the Invention Including Prior Art
Goldberg in Journal of Polymer Science, Part C, No. 4, pages 707 to 730 (1963) discloses polyether-polycarbonate-blockcopolymers prepared by reaction of about 95 to 65 weight percent bisphenol A and correspondingly of about 5 to 35 weight percent of a polyethyleneglycol with a corresponding amount of phosgene. Conventionally there were considerable difficulties to prepare such polycarbonate-polyether-blockcopolymers in a continuous process.
The discontinuous interfacial condensation process disclosed in German Offenlegungsschrift DE-OS No. 26 36 784 requires a very large excess of phosgene in order to reach sufficiently large reaction and employs the bisphenol A as its disodium salt. Therefor it was not possible to produce polymers having a relative viscosity of more than about 1.5 dl/g. The work up of the polymers obtained is difficult and requires considerable equipment based on the numerous separation and purification steps.
The preparation of polycarbonates by reacting 4,4'-bioxydiphenylalkanes with phosgene in the presence of pyridine and inert solvents is already disclosed in Angewandte Chemie, Vol. 68, page 635 (1956). As a suitable solvent for polycarbonates methylene chloride has previously been mentioned several times.